Couplings and fittings are components that enable ducts, cables, tubes and the like, which may generally be called “lines”, to be interconnected. Hydraulic couplings, for example, enable hydraulic lines containing hydraulic fluid to be interconnected to facilitate the functioning and minimize the damage of the hydraulic system.
Swivelling couplings are particularly desired since they enable the lines to move relative to one another. Such movement is especially required when flexible lines are used, and even more so when flexible lines are used in conjunction with dynamic heavy-duty industrial equipment. An example of such dynamic equipment is forestry equipment like feller-buncher machines and other multifunctional heads, which are used in the tight confines of wooded areas in proximity of very heavy trees and elevated forces. Feller-buncher machines have a variety of dynamic moving parts such as mechanical arms, claws, cylinders and motors. Of course, other industrial fields—such as the construction and mining industries—require large dynamic machinery as well. Often, the dynamic parts are powered hydraulically and, consequently, a variety of hydraulic systems—composed of hydraulic rotors, lines, couplings, control means, etc.—are employed.
Hydraulic systems have many preferable attributes, among which are adaptability, efficiency, heavy-dutiness, durability, dynamism, reliability and inexpensiveness.
Accessibility and ease of maintenance are very desirable characteristics of the coupling arrangement in any hydraulic system, especially those in which the couplings are arranged in awkward locations and orientations on the machine, which is done most of the time to protect the couplings from impacts and other damage-causing incidents.
In the prior art, lines are interconnected using a variety of fittings and couplings, some of which provide a rotation functionality between the lines. Often these couplings involve ball or needle bearings, which are susceptible to damage and have limited durability, especially when used in applications where they must endure strong axial forces and lateral impacts.
Furthermore, it is often desired to regroup a plurality of lines into a bundle or “cluster”, to organize the lines and to protect them from damages. Such clusters of lines must transport fluid to the required machine parts and depending on the geometrical constraints of the equipment the cluster may be forced to have a nonlinear and sometimes tortuous arrangement. The clusters often terminate at important locations in the hydraulic system. For instance, where hydraulic power is required at a head of a feller-buncher machine, the cluster may terminate in a bundle of fittings at an accessible location near the head, at which point each line may branch off to specific locations on the head.
Moreover, the cluster often supplies fluid to a dynamic part which may rotate, pivot or undergo a variety of other movements which cause the cluster of lines to sustain corresponding torsion, bending or other damaging forces. For example, a feller-buncher head may be rotatable and therefore the hydraulic lines supplying the necessary rotors, cylinders and/or other actuators must deal with these movements.
In the prior art, line clusters are regrouped and mounted to equipment by means of a variety of mounting means including standard clamps, bolts and screws, ropes, chains, homemade manifolds, among other connectors. The lines are sometimes fixedly mounted at their fittings to the super-structure of the machines. Line clusters are often held together using crude fastening means, to help put the couplings and/or fittings out of harm's way. However, this makes maintenance of the couplings very tedious and labour intensive, as the fastenings means must be undone to access a coupling.
In the prior art, line clusters are also regrouped and mounted to equipment using “bulkheads” or “manifolds”. For instance, a plurality of lines, each having a standard metallic fitting interconnecting two sides of the line, may be regrouped at a “plate bulkhead”. The fitting of each line is welded to a single plate bulkhead, which is in turn connected to the machine by a karabiner. These plate bulkheads offer limited maneuverability and as a consequence the lines are less adaptable to torsion constraints and are thus more susceptible to damage.
There are also “rotatable bulkheads” and “rotatable block manifolds” which interconnect line clusters while providing rotation between the two sides of the rotatable unit. The fittings are connected to the lines and are welded or otherwise secured to a plate. The plate is mounted within a bearing collar, which retains the plate and allows it to rotate. The bearing collar is then mounted to the machine, by a weld, a hinge or a karabiner, for example. These units enable some rotation functionality between the lines, but they are inefficient against torsion and many other dynamic forces. This may lead to damaged lines and/or disconnection of the lines from their fittings due to the torsion. This also provides limited rotation ability of the lines. These units may also be expensive and are inefficient in preventing costly damage to hydraulic lines in particular.